Rowing locomotion by a stonefly that possesses the ancestral pterygote condition of co-occurring wings and abdominal gills

A leading hypothesis for the origin of insect wings is that they evolved from thoracic gills that were serial homologues of the abdominal gills present in fossil pterygotes and in the nymphs of some modern mayflies, damselflies and stoneflies. Co-occurrence of thoracic wings and abdominal gills is the primitive condition for fossil pterygote insects, whereas the winged stage of modern insects almost exclusively lacks abdominal gills. Here we examine the locomotor behaviour and gill morphology of a stonefly, Diamphipnopsis samali (Plecoptera), which retains abdominal gills in the winged adult stage. This species can fly, but also uses its forewings as oars to accomplish rowing locomotion along the surface of water. The abdominal gills are in contact with both air and water during rowing, and their elaborately folded surface suggests an ability to contribute to gas-exchange. D. samali nymphs also have behaviours that place them in locations where their gills are exposed to air; they forage at night at the stream margin and within bubble curtains in rapids. These traits may exemplify an early pterygote condition in which gill and protowing function overlapped in an amphibious setting during a transition from aquatic to aerial locomotion and gas exchange. Rowing locomotion provides a novel and mechanically intermediate stage for the wings-from-gills and surface-skimming hypotheses for the origin of insect wings and flight.  © 2003 The Linnean Society of London, Biological Journal of the Linnean Society , 2003, 79, 341–349.     

From Molecules to Mating Success: Integrative Biology of Muscle Maturation in a Dragonfly

SYNOPSIS. Dragonflies begin adult life as comparatively weakfliers, then mature to become one of nature's ultimate flyingmachines. This ontogenetic transition provides an opportunityto investigate the relationship between life history, phenotypicplasticity, and changing ecological demands on organismal performance.Here we present an overview of a wide-ranging study of dragonflymuscle maturation that reveals i) ecological changes in theneed for efficient versus high-performance flight, ii) organism-level changes in performance, thermal physiology, locomotormechanics, and energy efficiency, iii) tissue-level changesin muscle ultrastructure and sensitivity to activation by calcium,and iv) molecular-level changes in the Lsoform composition ofa calcium regulatory protein in flight muscle (troponin-T).We discuss how these phenomena may be causally related, andthereby begin to show linkages across many levels of biologicalorganization. In particular, we suggest that alternative splicingof troponin-T mRNA is an important component of the "gearing"of muscle contractile function for developmental changes inwingbeat frequency and ecological demands on flight performance.Age-variable gearing of muscle function allows energeticallyeconomical flight during early adult growth, whereas power outputis maximized at maturity when aerial competition determinessuccess during territoriality and mating.     

Floral choices by honeybees in relation to the relative distances to flowers

ABSTRACT. Honeybees ( Apis mellifera L.) were presented with a series of binary choices between two equally rewarding yellow or blue artificial flowers. When flowers were placed equidistant from each other, the bees maintained high degrees of constancy to one flower colour. When flowers were spaced unequally, the bees most often chose to visit the closest flower, as is predicted by an optimal foraging model.